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Sunday, July 1, 2012

There is a lot of interest in sustainability, local agriculture, and permaculture these days. I had a discussion with a friend tonight: Could Greater Lowell grow its own food? It's sort of an artificial question as the area that comprises Greater Lowell is physically quite small - much smaller than you'd really want to count as hinterlands, but I'm always up for a little number crunching, so here's my (completely non-scientific) stab at it:

How many people in Greater Lowell and how much land?

This was by far the easiest part, and the only part with good, hard numbers. Wikipedia provides this data for recent years. Now, of course, much of the land is already built on and much of it is probably non-arable. Back to that later.

Municipality

Land area, in square miles

Population

Lowell

13.8

106519

Chelmsford

22.7

33802

Dracut

20.9

29457

Tewksbury

20.7

28961

Tyngsboro

16.9

11292

Billerica

25.9

40243

Westford

30.6

21951

Dunstable

16.6

3179

Total Population: 275,404Total Land (In acres [1 square mile=640 acres]):107,584. This works out to be a circle with a radius of about 7 miles. Again, compare to the concept of the 100-mile diet - a circle of over 20 million acres! Again, the Lowell Food Security Coalition seems to be looking at a 30-mile radius, and their goal doesn't seem to be total self-sufficiency.

How much land does it take to feed a person?

This was a lot harder as the answer is heavily dependent on numerous factors. One major factor of course is the type of diet a person eats. Beef, for example, takes a huge amount of land to raise compared to chickens compared to a vegetarian diet. That said, grazing animals can take advantage of land that vegetable farming cannot, so again, not that simple.

So, after spending some time on Google, I came across a Cornell study from the last five years that figured a series of diets using foods local to New York and how much land they would take. New York is at our latitude and has similar soil and rainfall numbers, so I figure it's a fair starting point. As I really only read this person's analysis (Can New York State Feed Itself?), it is not clear on how intensive the farming here discussed is - or how sustainable the practices are. Clearly, if the numbers don't factor in crop rotation or heavy use of chemical fertilizers and pesticides, more land would be needed to replenish the exhausted land over time. Either way, the studies for many diets came out between about half an acre and an acre per person. These numbers appear throughout many estimates on traditional agricultural methods I found online, so let's split the difference and say .75 acres will feed a person a reasonable and sustainable diet.

So how many people will that feed? How much land is there per person?

107,584 acres will feed 80,688 people, or under 1/3 of Greater Lowell. Remove Dunstable from the equation and a net 5,000 more would go hungry.

Not great numbers.

Now, we could all eat if we could sustainably eat on .39 acres of land a head. Of course, we don't have houses in this model yet. Let's all live at the average population density of Lowell: 7,500 people per square mile. That's 36.7 square miles given over to housing. Add in a few roads, schools, businesses and other non-agricultural uses ... call if 50 square miles, and that seems low. Remember that we should be feeding people out of their own yards when possible though and the 50 seems more fair. That's 32,000 acres taken off of potential food production either way.

Now we need to feed 275,404 people on .27 acres each. Would it be possible in any situation? Well, potatoes can produce somewhere in the neighborhood of ten million calories per acre (Google around - I saw estimates from six to 17 million!). So, on a quarter acre that's about 2.5 million calories / 365 days = 6,849 calories per day per acre. A person really only needs 2,500. So, if you could really live on just potatoes, and could grow them in the same soil year after year, it'd be no problem at all. My guess is that on any realistic diet it would be quite difficult for us to grow enough varied foods to feed ourselves. Probably impossible in reality.

How much food do we even produce today?

Well, according to the Northern Middlesex Council of Governments, there are under 6,500 acres listed as agricultural today in the seven towns I used (they also track Pepperell while I did not). Assuming that this farmland was split up in a way that represented complete diets instead of a heavy emphasis on say, dairy, and was always producing all the time, at half an acre required to feed a person, that's a mere 13,000 people fed.

I guess the answer is we have a long, long way to go if we wanted to be self-sufficient for food as a region. Again, the region we're talking about here is very artificially small. Even still, more carefully and scientifically gathered numbers are probably even worse: If the Cornell study said that the 35 million acres in New York State were not arable enough to feed 19 million New Yorkers, than the 6.7 million acres of land in Massachusetts couldn't possibly feed 6.5 million Bay Staters. The 275,000 Greater Lowellians - a densely urbanized area - have zero chance under any current farming model of feeding us on 100,000 acres.